As a method for determining the carbon content of steel material or for judging whether a steel material consists of a carbon steel or a low-alloy steel, there has been known a method in which an inspector visually observes a spark produced when the steel material is ground by a grinder or the like, and the inspector makes determination or judgment from the state of spark observed. Unfortunately, this method poses a problem that the accuracy of the determination or judgment is unstable, and also a skilled inspector is needed because the determination result or the judgment result depends on the skill of inspector.
A steel material inspection apparatus for making the above-described determination stably and accurately has been proposed (for example, refer to JP3482265B). Unfortunately, the steel material inspection apparatus described in JP3482265B cannot be used to make the above-described judgment stably and accurately. Therefore, it is still desired to develop an apparatus and method capable of making the above-described judgment stably and accurately.